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Publikationen - Natur- und Wirkstoffchemie

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Publikation

Lam, Y. T. H.; Palfner, G.; Lima, C.; Porzel, A.; Brandt, W.; Frolov, A.; Sultani, H.; Franke, K.; Wagner, C.; Merzweiler, K.; Wessjohann, L. A.; Arnold, N.; Nor-guanacastepene pigments from the Chilean mushroom Cortinarius pyromyxa Phytochemistry 165, 112048, (2019) DOI: 10.1016/j.phytochem.2019.05.021

For the first time, the pigment composition of basidiocarps from the Chilean mushroom Cortinarius pyromyxa was studied under various aspects like phylogeny, chemistry and antibiotic activity. A molecular biological study supports the monotypic position of C. pyromyxa in subgenus Myxacium, genus Cortinarius. Four undescribed diterpenoids, named pyromyxones A-D, were isolated from fruiting bodies of C. pyromyxa. Their chemical structures were elucidated based on comprehensive one- and two-dimensional NMR spectroscopic analysis, ESI-HRMS measurements, as well as X-ray crystallography. In addition, the absolute configurations of pyromyxones A-D were established with the aid of JH,H, NOESY spectra and quantum chemical CD calculation. The pyromyxones A-D possess the undescribed nor-guanacastane skeleton. Tested pyromyxones A, B, and D exhibit only weak activity against gram-positive Bacillus subtilis and gram-negative Aliivibrio fischeri as well as the phytopathogenic fungi Botrytis cinerea, Septoria tritici and Phytophthora infestans.
Publikation

Quang, D. N.; Wagner, C.; Merzweiler, K.; Abate, D.; Porzel, A.; Schmidt, J.; Arnold, N.; Pyrofomins A-D, polyoxygenated sesquiterpenoids from Pyrofomes demidoffii Fitoterapia 112, 229-232, (2016) DOI: 10.1016/j.fitote.2016.06.004

Pyrofomins A-D, four polyoxygenated sesquiterpenoids have been isolated from the methanolic extract of the fruit bodies of Pyrofomes demidoffii. Their structures are elucidated by IR, HR-FTICR-MS, and 2D NMR spectroscopy. Furthermore, the cedrane carbon skeleton of pyrofomin A (1) is confirmed by X-ray crystallographic analysis. The sesquiterpenoids 1–4 show neither cytotoxicity against KB cells nor antimicrobial activity.
Publikation

Bette, E.; Otto, A.; Dräger, T.; Merzweiler, K.; Arnold, N.; Wessjohann, L.; Westermann, B.; Isolation and Asymmetric Total Synthesis of Fungal Secondary Metabolite Hygrophorone B12 Eur. J. Org. Chem. 2015, 2357-2365, (2015) DOI: 10.1002/ejoc.201403455

Hygrophorone B12, a new antifungal constituent from the fruiting bodies of Hygrophorus abieticola, has been isolated and subsquently synthesized in enantiomerically pure form. The total synthesis includes a Sharpless asymmetric dihydroxylation protocol as the stereodifferentiating step, followed by two diastereoselective aldol‐type reactions. The approach allows the unambiguous control of all three stereogenic centres, and, furthermore, unequivocal determination of the relative and absolute configuration of antibiotic hygrophorones B for the first time.
Publikation

Tarman, K.; Palm, G. J.; Porzel, A.; Merzweiler, K.; Arnold, N.; Wessjohann, L. A.; Unterseher, M.; Lindequist, U.; Helicascolide C, a new lactone from an Indonesian marine algicolous strain of Daldinia eschscholzii (Xylariaceae, Ascomycota) Phytochem. Lett. 5, 83-86, (2012) DOI: 10.1016/j.phytol.2011.10.006

From an endophytic Daldinia eschscholzii strain isolated from the agar-producing red alga Gracilaria sp. SGR-1, collected from the coast of South Sulawesi, Indonesia, a new lactone helicascolide C (1) was obtained as colourless crystals from the ethyl acetate extract together with the related structurally known compound helicascolide A (2). The structure of the new compound 1 reveals a carbonyl group replacing an alcohol group of compound 2. The structure of 1 was elucidated by X-ray diffraction and spectral analyses. Compound 1 showed fungistatic activity against the phytopathogenic fungus Cladosporium cucumerinum.
Publikation

Westermann, B.; Michalik, D.; Schaks, A.; Kreye, O.; Wagner, C.; Merzweiler, K.; Wessjohann, L. A.; Natural Product Inspired meta/para’-Biaryl Ether Lactam Macrocycles by Double Ugi Multicomponent Reactions Heterocycles 73, 863-872, (2007) DOI: 10.3987/COM-07-S(U)21

Isonitrile meta/para’-functionalized biaryl ethers can serve as key building blocks for the highly efficient and diverse one step production of natural product inspired peptide/peptoid macrocycles, thereby forming up to 54-membered rings with eight or even sixteen new bonds. Aliphatic diamine and diacid tethers give access to two different classes of biaryl ether cyclopeptoids, either with exo/endo or exclusively endo dipeptidic moieties.
Publikation

Voigt, B.; Porzel, A.; Adam, G.; Golsch, D.; Adam, W.; Wagner, C.; Merzweiler, K.; Synthesis of 2,24-Diepicastasterone and 3,24-Diepicastasterone as Potential Brassinosteroid Metabolites of the Cockroach Periplaneta americana Collect. Czech. Chem. Commun. 67, 91-102, (2002) DOI: 10.1135/cccc20020091

Investigations of the metabolic conversion of the phytohormone 24-epicastasterone (1) in the cockroach Periplaneta americana (L.) required the synthesis of 2,24-diepicastasterone (4), 3,24-diepicastasterone (7b) and 2-dehydro-3,24-diepicastasterone (9) as reference standards. 2,24-Diepicastasterone (4) was synthesized from 2α,3α-epoxy derivative 2 as well as from the 2β,3β-epoxy-22,23-diol 3 by acid-catalyzed water addition to the epoxy function leading to the desired 2β,3α-trans functionality. 3,24-Diepicastasterone (7b) was prepared by NaBH4-reduction of the 3-oxo derivative 6. Upon deprotection conditions from the ketol acetonides 6 and 8 in both cases 2-dehydro-3,24-diepicastasterone (9) was obtained. The structure of 2,24-diepicastasterone (4) was confirmed by X-ray analysis.
Publikation

Porzel, A.; Phuong Lien, T.; Schmidt, J.; Drosihn, S.; Wagner, C.; Merzweiler, K.; Van Sung, T.; Adam, G.; Fissistigmatins A–D: Novel Type Natural Products with Flavonoid–Sesquiterpene Hybrid Structure from Fissistigma bracteolatum Tetrahedron 56, 865-872, (2000) DOI: 10.1016/S0040-4020(99)01049-2

From Fissistigma bracteolatum Chatt. (Annonaceae), a Vietnamese folk medicinal plant, the novel type natural products fissistigmatin A–D (1–4), being composed of a flavonoid and a sesquiterpene moiety, were isolated. Their structures were elucidated by extensive NMR techniques, MS, CD, molecular modelling calculations and X-ray analysis.
Publikation

Phuong, N. M.; Van Sung, T.; Porzel, A.; Schmidt, J.; Merzweiler, K.; Adam, G.; β-Carboline alkaloids from Hedyotis capitellata Phytochemistry 52, 1725-1729, (1999) DOI: 10.1016/S0031-9422(99)00280-0

Three new β-carboline alkaloids were isolated from Hedyotis capitellata (Rubiaceae). Their structures were elucidated by spectroscopic data and X-ray analysis.
Publikation

Drosihn, S.; Porzel, A.; Voigt, B.; Brandt, W.; Wagner, C.; Merzweiler, K.; Adam, G.; Conformational studies of two new brassinosteroid analogues with a 22,23-trans diol function J. Chem. Soc., Perkin Trans. 2 1999, 233-238, (1999) DOI: 10.1039/A807440B

22,24-Diepiteasterone (3) and 23,24-diepiteasterone (4) were synthesized starting from a mixture of the corresponding (22S,23S)- and (22R,23R)-epoxides. Using detailed NOE investigations and molecular dynamic simulations with explicit solvent, the preferred conformations of both compounds were determined in solution. For both compounds 3 and 4 a preferred conformation of the side chain was found. For 4, by X-ray analysis the conformation in crystalline state was determined which differs distinctly from that in solution.
Publikation

Lien, T. P.; Ripperger, H.; Porzel, A.; Merzweiler, K.; Sung, T. V.; Adam, G.; Indole alkaloids from tabernaemontana bovina Phytochemistry 49, 1457-1461, (1998) DOI: 10.1016/S0031-9422(98)00127-7

In addition to (-)-mehranine, hecubine, ibogaine, ibogaline, 19R-epi voacristine, 20-hydroxyconopharyngine and pedunculine the novel indole alkaloids 3-oxomehranine and 14α,15β-dihydroxy-N-methylaspidospermine have been isolated from the leaves and stems of Tabernaemontana bovina. The structure of 3-oxomehranine has been assigned by NMR investigations, the structure of 14α,15β-dihydroxy-N-methylaspidospermine by X-ray analysis and their absolute configurations by circular dichroism.
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